The principal functions of Core B, the Clinical Core of the of the ADRC, are: to recruit, characterize and follow subjects as part of our clinical and neurobiological investigations of normal aging and AD; and to provide a resource for all investigators at JHMI involved in the investigation of aging and AD, including clinical trials, genetic studies, imaging studies, and neuropathological neurochemical analyses of brain. Because cognitive performance in the elderly varies widely, ranging from normal cognition to severe dementia, the staff of Core B has assembled several cohorts (approximately 700 subjects) to examine the full spectrum of cognitive states associated with old age. The centerpiece of ore B, however, is investigations of non-demented elderly subjects and patients in the early stages of AD. Thus, Core B has enrolled approximately 500 normal subjects of the BLSA as well as 100 subjects with early AD and approximately 75 controls (Cohort 2), in addition to the remaining 25 severely demented members of the original ADRC cohort (Cohort 1). Significantly, more than one-third of all AD patients recruited in the last funding period were African-Americans, a group which has been under-represented in studies of AD. Cohorts 1 and 2 are used for our investigations of AD, whereas the BLSA cohort serves as the focus for our clinical, and neuropathological studies of normal aging and early stages of dementia. The Biostatistics & Data Center, staffed by professionals with expertise in statistical methods for longitudinal studies and analytical approaches to data management, functions to collect, maintain, and analyze the demographic and clinical information on all subjects and to facilitate our data sharing efforts, particularly with the ADC Data Coordinating Center. The staff of Core B, with expertise in neurology, psychiatry, biostatistics, and nursing, interacts closely with investigators in Core C and supports research in Project 4. Complementing the investigations of experimental models (Projects 1-3) in our ADRC, Core B is a central clinical resource for all investigations of human subjects in the ADRC and for other investigations at JHMI.